1. Field of the Invention
The present invention relates to an information processing apparatus, method, and a program. In particular, the present invention relates to an information processing apparatus, method, and a program which make it possible to appropriately perform color gamut conversion of content data.
2. Description of the Related Art
Recently, various kinds of digital image devices having different color representation areas have been increasing. As a method for coinciding colors with each other between devices having different color gamuts to output the coincident colors, a workflow has been proposed on the basis of an sRGB (standard RGB) that is the standard color space for monitors in the related art. However, with the appearance of many digital still cameras and video cameras capable of capturing colors outside the sRGB color gamut, many methods for color gamut conversion (i.e. compression/decompression) have been proposed as methods of smoothly outputting captured wide color gamut image data to devices having various color gamuts including wide color gamut displays and printers with suppression of color inconsistency or high-luminance and high-saturation color bleeding.
As methods for color gamut conversion, for example, there are a method having a complicated color gamut shape after conversion and a method having a simplified color gamut shape after conversion.
A complicated color gamut has the same shape as the color gamut of, for example, a print device such as a printer or the like. Generally, in the case of the print device, the color forming method is complicated due to the ink characteristics or the paper characteristics, and thus the shape of the color gamut, which is the color range that the device can reproduce, also becomes complicated.
In contrast, a simplified color gamut has the same shape as the color gamut of, for example, a display device such as an RGB monitor or the like. Generally, in the case of the display device, the color forming is performed by additive color mixing of light that RGB phosphors emit, and thus the shape of the color gamut, which is the color range that the device can reproduce, becomes simplified.
FIG. 1 is a diagram illustrating examples of compared shapes of various kinds of color gamuts.
As illustrated in FIG. 1, in the case of an Adobe RGB color gamut 1 or an sRGB color gamut 2 for a display device, the shape of the color gamut is simplified, for example, as its external shape is roughly in the form of a straight line. In contrast, a printer color gamut 3 for a print device has a complicated shape, for example, in which its whole external shape is roughly in the form of a curve.
Diverse methods for the color gamuts of images have been proposed, and methods that correspond to the complicated shape have also been proposed (e.g. see Japanese Unexamined Patent Application Publication No. 2000-278546 (corresponding to U.S. Pat. No. 6,437,792) and Japanese Unexamined Patent Application Publication No. 2007-158948).
For example, in Japanese Unexamined Patent Application Publication No. 2000-278546 (corresponding to U.S. Pat. No. 6,437,792), performing of color gamut conversion so that the color difference in a uniform color perception space is at a minimum by using a non-linear operation to correspond to even a complicated color gamut shape has been proposed. Also, for example, in Japanese Unexamined Patent Application Publication No. 2007-158948, a method of converting color gamut as preserving a gray axis using 3DLUT has been proposed.
In contrast, methods that correspond to the simplified shape have also been proposed (e.g. see Japanese Unexamined Patent Application Publication No. 2007-142494 and Japanese Unexamined Patent Application Publication No. 2003-244458). In Japanese Unexamined Patent Application Publication No. 2007-142494, a method of performing color gamut compression in a state where the space for performing the image process is kept RGB, almost linear operations are used and the color values are preserved has been proposed. Also, in Japanese Unexamined Patent Application Publication No. 2003-244458, a method of realizing simplified color gamut compression which can maintain the grayscale and adjust a used compression table by hue as performing the process in a state where RGB is kept as the color space has been proposed.
Generally, in the case of the color gamut conversion that corresponds to even the complicated color gamut shape, the load is large and a long operation time is necessary. Accordingly, it is not suitable to the color gamut conversion of a moving image that necessitates real-time (i.e. instant) image output.
Also, in the case of the method corresponding to the simplified color gamut shape, it is general that, although the load is small and high-speed operation is possible, the shape of the color gamut that can be used is limited or adjustable parameters are greatly limited in comparison to the method corresponding to the high-definition color gamut shape. Accordingly, unnatural appearance may occur depending upon the light source for observing the image or the scene of an image.
Since the methods proposed as described above have diverse advantages and defects, it is convenient if the color gamut conversion algorithms can be selectively used according to their purposes.
In contrast, methods for selectively using color gamut conversion algorithms have been proposed (e.g. Japanese Unexamined Patent Application Publication Nos. 2002-218271, 2002-314828, and 2005-318491). For example, in Japanese Unexamined Patent Application Publication No. 2002-218271, appropriate selection of one of a plurality of color gamut compression methods according to the kind of input manuscript has been proposed. In Japanese Unexamined Patent Application Publication No. 2002-314828, changing of color gamut conversion methods in accordance with the types of a plurality of subjects (e.g. natural images, graphics, texts, and the like) which exist together in one document has been proposed. Further, in Japanese Unexamined Patent Application Publication No. 2005-318491, a method of selecting one of plural algorithms (i.e. gamut mapping algorithms (GMA)) that perform color gamut mapping using ICC profiles prescribed in ICC (International Color Consortium) has been proposed.
Also, a method of dividing processing of a still image and a moving image has been considered (e.g. see Japanese Unexamined Patent Application Publication No. 2002-182634). In Japanese Unexamined Patent Application Publication No. 2002-182634, a method of automatically switching color reproduction methods according to differences between a still image and a moving image has been proposed.